DOCSLIB.ORG

Management of Anisometropic Amblyopia: a Case Report and Brief Review

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Management of Anisometropic Amblyopia: a Case Report and Brief Review Management of fit with soft contact lenses to achieve optimal Anisometropic Amblyopia: vision and binocularity. Part-time occlusion therapy was also initiated, which was modified A Case Report and throughout the treatment period based on Brief Review clinical findings. She was also treated with Sung Hee (Kelly) Lee, OD, FAAO 19 sessions of office-based vision therapy in order to maximize the success of amblyopia Graham B. Erickson, OD, FAAO, treatment. At the completion of the treatment, FCOVD this patient showed significant improvement in her visual acuity and other non-acuity factors, including contrast sensitivity and binocularity. ABSTRACT Background Conclusions ARTICLE Unilateral functional amblyopia due The successful treatment of this patient with to anisometropia is a common cause anisometropic amblyopia was achieved by of vision loss in children. There has been a the combination of active vision therapy with significant amount of research recently to evidence-based management strategies, determine the most effective management consisting of optical correction and occlusion strategies for such cases, and it is important therapy. for clinicians to determine how to apply these findings clinically. INTRODUCTION Anisometropia is a common cause of Case Report functional amblyopia. It is often difficult to A 6-year-old female presented for her first detect without an effective vision screening or comprehensive eye exam after failing a school a comprehensive eye examination, as there are vision screening. She was diagnosed with typically no symptoms or obvious manifesting significant anisometropia with anisometropic signs. amblyopia in her left eye. She was treated with A generally accepted definition of aniso- spectacle correction initially, and was eventually metropia is at least 1D difference of sphere or cylinder power between each eye.1,2,3,4 The Correspondence regarding this article should be potential amblyogenic amount of anisometropia emailed to Sung Hee (Kelly) Lee, OD, FAAO, at is suggested to be 1D for hyperopia, 3D [email protected]. All state ments are the authors’ 5 personal opinions and may not reflect the opinions of for myopia, and 1.5D for astigmatism. The the College of Optometrists in Vision Development, reported incidence of amblyopia is 100% with Vision Development & Rehabilitation or any institution hyperopic anisometropia of 3.5D or higher, or organization to which the authors may be affiliated. Permission to use reprints of this article must be obtained and in myopic anisometropia of 6.5D or from the editor. Copyright 2019 College of Optometrists higher.1,2,6,7 in Vision Development. VDR is indexed in the Directory of Open Access Journals. Online access is available at In anisometropic amblyopia, visual depriv- covd.org. https://doi.org/10.31707/VDR2019.5.2.p100 ation and the subsequent lack of adequate retinal stimulus are caused by optical defocus Lee SHK, Erickson GB. Management of anisometropic amblyopia: A case report and brief review. Vision Dev & and abnormal binocular inhibition in the Rehab 2019;5(2):100-12. more ametropic eye.1,3,6,8,9 In addition to acuity loss, these mechanisms also affect the normal development of other vision factors Keywords: Amblyopia; Anisometropia; including contrast sensitivity, accommodation, Vision Therapy oculomotor function, and eye-hand coordina- 100 Vision Development & Rehabilitation Volume 5, Issue 2 • June 2019 tion.1,2,3,6,10 Another considerable factor is the no afferent pupillary defect in both eyes. The compromised binocularity in these patients. confrontation visual fields were grossly full, Even after improvement of vision and deficient and extraocular muscle motilities were full vision skills in the amblyopic eye, aniseikonia and unrestricted in each eye. Cover testing and binocular inhibition patterns can remain as revealed ortho alignment at distance and obstacles for obtaining sensory fusion without 6Δ exophoria at near. No stereo acuity was further intervention. reported with the Lang I stereoacuity test. The In addition to recognizing the risk factors following are the results of objective refraction: and clinical findings described above, the appropriate evidence-based management Dry Retinoscopy: strategies that should be considered for OD: +1.00D patients with anisometropic amblyopia include OS: +8.50-1.25x004 optical correction and occlusion. Further, active vision therapy (VT) should also be considered Wet Retinoscopy to potentially improve the efficacy and (1gtt 1% cyclopentolate OU): facilitate the efficiency of the treatment. This OD: +2.00D case report demonstrates an effective course OS: +9.00-1.00x175 of treatment for anisometropic amblyopia using all of these strategies. Anterior and posterior segment ocular health were unremarkable. CASE Based on the findings, AC was diagnosed AC, a 6-year-old female, presented for her with refractive amblyopia in the left eye first comprehensive eye exam after failing a secondary to high hyperopic anisometropia school vision screening. This first grader was of 6.5D (equivalent sphere). A spectacle told that her left eye was not “focusing” as correction was chosen over contact lenses since well as the right eye. Another optometrist protection of the sound eye was one of the at the clinic initiated the vision care of AC, treatment goals due to the severe amblyopia. before care was transferred to the authors. However, contact lenses to minimize anisei- AC’s mother reported no noticeable problems konia were strongly recommended as a future regarding her eyes or vision and AC never option as the amblyopia resolves. A spectacle reported any complaints. AC’s health history prescription of +1.00D OD and +8.00- was unremarkable and the pregnancy and 1.00x175 OS was provided for full time wear. birth histories were normal. She was meeting The importance of compliance with spectacle normal developmental milestones and not wear was emphasized and she was advised to experiencing any difficulties at school. She return to the clinic in 6 weeks for a follow-up reported an allergy to penicillin that causes evaluation of her prescription and amblyopia. a rash, and was taking no medication other than a multivitamin supplement. There was no Follow-Up Visit #1 known family history of any ocular conditions. AC’s mother reported good compliance with spectacle wear. The corrected distance Initial Exam visual acuities were 20/20 (1.0MAR) OD and AC’s uncorrected vision in the right eye 20/125- (6.3-MAR) OS with isolated single line was 20/20 (1.0MAR) at both distance and near; Snellen acuity. She demonstrated 400 arc however, the left eye was 20/250- (12.5-MAR) seconds of local stereo acuity with Wirt-type at distance and 20/200- (10.0-MAR) at near. circles on the Randot steroacuity test. The The pupils were equally reactive to light with over-retinoscopy findings through the current 101 Vision Development & Rehabilitation Volume 5, Issue 2 • June 2019 spectacles revealed +1.25D OD and +0.25- with the Snellen single line, 20/50 (2.0MAR) 0.25x180 OS. The prescription was not modified with single letter, and 20/60- (3.0- MAR) with at this time, and it was decided to monitor. crowded Lea symbols. She reported no global AC’s optometrists at this visit initiated 2 hours stereo with the Randot butterfly stereoacuity of daily patching of the right eye with a Patch- test and 100 arc seconds of local stereo with works eye patch to expedite the recovery of the animals on the Randot test. The 3-Figure visual acuity. AC was recommended to engage Worth test revealed suppression of the left eye in eye-hand coordination activities at near at distances farther than 1 meter. Visuoscopy while patching. A follow-up appointment was testing showed steady central fixation in the scheduled in 1 month. right eye and unsteady central fixation in the left eye. The clinical findings measured at Follow-Up Visit #2 this visit are summarized in Table 2. AC was AC still reported good compliance with recommended to attempt increasing patching spectacle wear. However, patching was to 2 hours a day while engaging in near eye- reported to be extremely difficult, and it could hand activities. The option of a contact lens only be done for about 30 minutes each day. correction was discussed again. AC’s mother The corrected distance visual acuity in the left was informed about the option of active vision eye improved to 20/80- (4.0-MAR) with Snellen therapy to potentially increase the efficacy of single line and 20/70 (3.5MAR) with Snellen occlusion therapy, decrease the treatment isolated letter. Over-retinoscopy results were duration, train the vision skill deficits in the consistent with the first follow-up visit, so the amblyopic eye, and maximize binocularity. right eye’s prescription was updated to +2.00D After the discussion, it was decided to pursue from +1.00D. The left eye’s prescription a contact lens correction and initiate a weekly remained unchanged. She was recommended vision therapy program. to try patching the right eye for 2 hours/ day, 7 days/week, and was educated on the Active Vision Therapy Program (28 weeks) importance of compliance with occlusion Active Vision Therapy therapy for maximum benefit. The next follow- Weekly 45-minute in-office vision therapy up visit was scheduled in 1 month. sessions were conducted, and AC’s visual acuity in her left eye was measured at Follow-Up Visits #3-5 each visit. In addition to daily patching, These follow-up visits were conducted in approximately 35 minutes of home therapy monthly intervals. AC had difficulty and poor was prescribed for 5 days each week. The compliance with the patching regimen of 2 compliance with in-office visits was good, with hours per day that was prescribed. For follow- moderate compliance with the prescribed up visits #3 and #4, minimal improvement home therapy activities. Progress evaluations of the VA in the left eye was measured.
Load more

Recommended publications
  • Prescription Companion
    PRESCRIPTION COMPANION ©2012Transitions Optical inc. ophthalmic lens technical reference JUBILEE YEAR 2012 E -Edition 7 www.norville.co.uk Introduction and Page Index The Norville Companion is a supporting publication for our Prescription Catalogue, providing further technical details, hints and ideas gleaned from everyday experiences. TOPIC Page(s) TOPIC Page(s) Index 2 - 3 Part II Rx Allsorts Lens Shapes 4 - 6 Lens Forms 49 Effective Diameter Chart 7 Base Curves 50 - 51 Simplify Rx 8 Aspherics 52 - 53 Ophthalmic Resins 9 Free-form Digital Design 54 Indices of Ophthalmic lenses - Resin 10 Compensated Lens Powers 55 - 56 Polycarbonate 11 Intelligent Prism Thinning 57 - 58 Trivex 12 - 13 Superlenti - Glass 59 Resin Photochromic Lenses 14 Superlenti - Resin 60 Transitions Availability Check List 15 V Value / Fresnels 61 Nupolar Polarising Lenses 16 E Style Bifocal / Trifocal 62 Drivewear Lenses 17 - 18 Photochromic / Glazing / Prisms 63 UV Protective Lenses 19 Lens Measures 64 Norville PLS Tints 20 Sports 65 Tinted Resin Lenses 21 3D Technology Overview 66 Mid and High Index Resins Tintability 22 Rx Ordering 67 Norlite Tint Transmission Charts 23 - 25 Order Progress 68 Norlite Speciality Tinted Resins 26 - 31 Rx Order Form 69 Norlite Mirror Coating 32 Queries 70 Reflection Free Coating 33 - 34 Optical Heritage 71 F.A.Q. Reflection Free Coatings 35 - 37 Rx House - Change afoot? 72 - 73 Indices of Ophthalmic Lenses - Glass 38 Remote Edging 74 Glass Photochromic Lenses 38 Remote edging - F.A.Q. 75 Speciality Absorbing Glass 39 Quality Assurance
    [Show full text]
  • WSPOS Worldwide Webinar 16: Amblyopia - How and When
    Answers to Audience Questions - WSPOS Worldwide Webinar 16: Amblyopia - How and When WWW 16 Panellists Anna Horwood Celeste Mansilla David Granet Krista Kelly Lionel Kowal Susan Cotter Yair Morad Anna Horwood (AH), Celeste Mansilla (CM), Krista Kelly (KK), Lionel Kowal (LK), Susan Cotter (SC), Yair Morad (YM) 1. How do you maintain attained iso visual acuity after successful amblyopia treatment? AH: Intermittent monitoring. If they have regressed previously, I might carry on very intermittent occlusion (an hour or two a week) until I was sure it was stable. CM: With gradual and controlled reduction of the treatment, for example: if the patient had 1 hour of patch per day, I leave it with 1 hour 3 times a week during a month. I do a check and if the visual acuity was maintained, I lower patches to 2 times a week. I keep checking and going down like this until I suspend the treatment. If at any time I detect worsening visual acuity, I return to the previous treatment. SC: Best way is attainment of normal binocular vision. I do not worry about ansiometropic amblyopes who have random dot stereopsis post-treatment. If have constant unilateral strabismus, I can do some limited part-time patching, decreasing patching dosage over time given no regression of VA. YM: repeat examination every 6 months. If I see regression, I will prescribe patching for 30 min a day. 2. How do you plan for very dense amblyopes? AH: I very rarely see them because, with screening, they are picked up early and usually do well.
    [Show full text]
  • The Eye Is a Natural Optical Tool
    KEY CONCEPT The eye is a natural optical tool. BEFORE, you learned NOW, you will learn •Mirrors and lenses focus light • How the eye depends on to form images natural lenses •Mirrors and lenses can alter • How artificial lenses can be images in useful ways used to correct vision problems VOCABULARY EXPLORE Focusing Vision cornea p. 607 How does the eye focus an image? pupil p. 607 retina p. 607 PROCEDURE 1 Position yourself so you can see an object about 6 meters (20 feet) away. 2 Close one eye, hold up your index finger, and bring it as close to your open eye as you can while keeping the finger clearly in focus. 3 Keeping your finger in place, look just to the side at the more distant object and focus your eye on it. 4 Without looking away from the more distant object, observe your finger. WHAT DO YOU THINK? • How does the nearby object look when you are focusing on something distant? • What might be happening in your eye to cause this change in the nearby object? The eye gathers and focuses light. The eyes of human beings and many other animals are natural optical tools that process visible light. Eyes transmit light, refract light, and respond to different wavelengths of light. Eyes contain natural lenses that focus images of objects. Eyes convert the energy of light waves into signals that can be sent to the brain. The brain interprets these signals as shape, brightness, and color. Altogether, these processes make vision possible. In this section, you will learn how the eye works.
    [Show full text]
  • Patient Instruction Guide
    1‐DAY ACUVUE® MOIST Brand Contact Lenses 1‐DAY ACUVUE® MOIST Brand Contact Lenses for ASTIGMATISM 1‐DAY ACUVUE® MOIST Brand MULTIFOCAL Contact Lenses etafilcon A Soft (hydrophilic) Contact Lenses Visibility Tinted with UV Blocker for Daily Disposable Wear PATIENT INSTRUCTION GUIDE CAUTION: U.S. Federal law restricts this device to sale by or on the order of a licensed practitioner. 1 TABLE OF CONTENTS TABLE OF CONTENTS ............................................................................................................................................... 2 INTRODUCTION ....................................................................................................................................................... 3 SYMBOLS KEY .......................................................................................................................................................... 4 UNDERSTANDING YOUR PRESCRIPTION ................................................................................................................. 5 GLOSSARY OF COMMONLY USED TERMS ............................................................................................................... 5 WEARING RESTRICTIONS & INDICATIONS ............................................................................................................... 6 WHEN LENSES SHOULD NOT BE WORN (CONTRAINDICATIONS) ............................................................................ 6 WARNINGS .............................................................................................................................................................
    [Show full text]
  • Strabismus, Amblyopia & Leukocoria
    Strabismus, Amblyopia & Leukocoria [ Color index: Important | Notes: F1, F2 | Extra ] EDITING FILE ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Objectives: ➢ Not given. Done by: Jwaher Alharbi, Farrah Mendoza. ​ ​ Revised by: Rawan Aldhuwayhi ​ Resources: Slides + Notes + 434 team. ​ ​ NOTE: F1& F2 doctors are different, the doctor who gave F2 said she is in the exam committee so focus on her notes Amblyopia ● Definition Decrease in visual acuity of one eye without the presence of an organic cause that explains that decrease ​ ​ in visual acuity. He never complaints of anything and his family never noticed any abnormalities ​ ● Incidence The most common cause of visual loss under 20 years of life (2-4% of the general population) ● How? Cortical ignorance of one eye. This will end up having a lazy eye ​ ● binocular vision It is achieved by the use of the two eyes together so that separate and slightly dissimilar images arising in each eye are appreciated as a single image by the process of fusion. It’s importance 1. Stereopsis 2. Larger field If there is no coordination between the two eyes the person will have double vision and confusion so as a compensatory mechanism for double vision the brain will cause suppression. The visual pathway is a plastic system that continues to develop during childhood until around 6-9 years of age. During this time, the wiring between the retina and visual cortex is still developing. Any visual problem during this critical period, such as a refractive error or strabismus can mess up this developmental wiring, resulting in permanent visual loss that can't be fixed by any corrective means when they are older Why fusion may fail ? 1.
    [Show full text]
  • Intraocular Lenses and Spectacle Correction
    MEDICAL POLICY POLICY TITLE INTRAOCULAR LENSES, SPECTACLE CORRECTION AND IRIS PROSTHESIS POLICY NUMBER MP-6.058 Original Issue Date (Created): 6/2/2020 Most Recent Review Date (Revised): 6/9/2020 Effective Date: 2/1/2021 POLICY PRODUCT VARIATIONS DESCRIPTION/BACKGROUND RATIONALE DEFINITIONS BENEFIT VARIATIONS DISCLAIMER CODING INFORMATION REFERENCES POLICY HISTORY I. POLICY Intraocular Lens Implant (IOL) Initial IOL Implant A standard monofocal intraocular lens (IOL) implant is medically necessary when the eye’s natural lens is absent including the following: Following cataract extraction Trauma to the eye which has damaged the lens Congenital cataract Congenital aphakia Lens subluxation/displacement A standard monofocal intraocular lens (IOL) implant is medically necessary for anisometropia of 3 diopters or greater, and uncorrectable vision with the use of glasses or contact lenses. Premium intraocular lens implants including but not limited to the following are not medically necessary for any indication, including aphakia, because each is intended to reduce the need for reading glasses. Presbyopia correcting IOL (e.g., Array® Model SA40, ReZoom™, AcrySof® ReStor®, TECNIS® Multifocal IOL, Tecnis Symfony and Tecnis SymfonyToric, TRULIGN, Toric IO, Crystalens Aspheric Optic™) Astigmatism correcting IOL (e.g., AcrySof IQ Toric IOL (Alcon) and Tecnis Toric Aspheric IOL) Phakic IOL (e.g., ARTISAN®, STAAR Visian ICL™) Replacement IOLs MEDICAL POLICY POLICY TITLE INTRAOCULAR LENSES, SPECTACLE CORRECTION AND IRIS PROSTHESIS POLICY NUMBER
    [Show full text]
  • Contact Lenses
    Buying Contact Lenses Some common Questions and Answers to help you buy your lenses safely Wearing contact lenses offers many benefits. Following some simple precautions when buying lenses can help to make sure that you don’t put the health and comfort of your eyes at risk. The British Contact Lens Association and General Optical Council have put together some common questions and answers to help you buy your lenses safely 2 Images courtesy of College of Optometrists, General Optical Council and Optician How do I find out about wearing contact lenses? ● If you want to wear contact lenses to correct your eyesight, you must start by consulting an eye care practitioner for a fitting. Only registered optometrists, dispensing opticians with a specialist qualification (contact lens opticians) and medical practitioners can fit contact lenses. Fitting includes discussing your visual and lifestyle requirements, an eye examination to make sure your eyes are healthy and find out if you’re suitable, and measurements of your eyes to ensure the best lens type, fit and vision, before trying lenses. Once you have worn the lenses, you should have the health of your eyes checked again. You will also need to learn how to handle and care for your lenses. Your practitioner will advise you when you should wear the lenses and how often you should replace them. When is the fitting completed? ● Your prescribing practitioner will tell you when the fitting is completed. How long the fitting takes will depend on your lens type and your eye health. Don’t forget that, once fitted, you will need to have regular check-ups to make sure your eyes are healthy and to get the best from your contact lenses.
    [Show full text]
  • Cataract Surgery and Diplopia
    …AFTER CATARACT SURGERY Lionel Kowal RVEEH Melbourne חננו מאתך דעה בינה והשכל DISTORTION Everything in my talk is distorted by selection bias I don‟t do cataract surgery. I don‟t see the numerous happy pts that you produce I see a small Array of pts with imperfect outcomes that may /not be due to the cataract surgery DIPLOPIA AFTER CATARACT SURGERY ‘Old’ reasons ‘New’ reasons : Normal or near- normal muscle function: usually ≥1 ‘minor’ stresses on sensory & motor fusion Inf Rectus contracture after -- Anisometropia: Monovision & -caine damage Aniseikonia Other muscles damaged by -caine Metamorphopsia 2ary to macular disease Incidental 4ths and occult Minor acquired motility changes Graves‟ Ophthalmopathy of the elderly: Sagging eye uncovered by cataract surgery muscles Old, Rare & largely forgotten Other sensory issues: Big Amblyopia: fixation switch difference in contrast between Hiemann Bielschowsky images, large field defects. „OLD‟ REASONS : -CAINE TOXICITY IS IT A PERI- OR RETRO- BULBAR? If you add an EMG monitor to your injecting needle, whether you think you are doing a Retro- or Peri- Bulbar, you are IN the inf rectus ~ ½ of the time* *Elsas, Scott „OLD‟ REASONS : -CAINE TOXICITY CAN BE ANY MUSCLE, USU IR, ESP. LIR Day 1: LIR paresis : left hyper, restricted L depression, diplopia : everyone anxious ≤1% Day 7-10: diplopia goes : everyone happy Week 2+: LIR fibrosis begins - diplopia returns : left hypo, vertical & torsional diplopia, restricted L elevation: everyone upset 0.1-0.2% Hardly ever gets better Spontaneous recovery from inferior rectus contracture (consecutive hypotropia) following local anesthetic injury. Sutherland S, Kowal L. Binocul Vis Strabismus Q.
    [Show full text]
  • Comparative Analysis of Cosmetic Contact Lens Fitting By
    Report of the Staff to the Federal Trade Commission A Comparative ~alysis of Cosmetic Coritact Lens Fitting by Ophtha1ffiologists, Optometrists, and Opticians .,... ... ---. ) by . Gary D. Hailey· Jonathan R. Bromberg Joseph P. Mulholland (Note: This report has been prepared by staff members of the Bureau of Consumer Protection and Bureau of Economics of the Federal Trade Commission. The Commission has reviewed the report and authorized its publication.) Acknowledgements The authors owe an enormous debt of gratitude to the many ophthalmologists, optometrists, and opticians wh~ assisted in the design and performance of this study out of a sense of responsi­ bility to their professions and to the public. Not all of them can be listed here. &ut the following individuals, who repre-. sen ted their respective professions at all stages of th~ study,' deserve special mention: Oliver H. Dabezies, Jr;, M.D., of the' Contact Lens Association of Ophthalmology and the American Academy of Ophthalmology; Earle L. Hunter, O.D., of the American Optometric Association; and Frank B. Sanning and Joseph W. Soper, of the Contact Lens Society of America and the Opticians Associa­ tion of America. Of course, none of these individuals or asso­ ciations necessarily endorses the ultimate conclusions of this report. A number ,of current and former FTC staff members have con­ tr ibuted to the study in important ways.· "'''Me-iribers of the Bureau of Consumer Protection's Impact Evaluation Unit, including Tom Maronick, Sandy Gleason,' Ron Stiff, Michael Sesnowitz, and Ken Bernhardt, helped answer innumerable technical questions related to the design and administration of the study. Christine Latsey, Elizabeth Hilder, Janis Klurfeld, Scott Klurfeld, Erica Summers, Matthew Daynard, Te~ry Latanich, and Gail Jensen interviewed study subjects, supervised the field examinat~ons, prepared data for analysis, wrote preliminary drafts, and helped with a number 6f 6ther ~asks.
    [Show full text]
  • Amblyopia HANDOUT ACES
    AMBLYOPIA CORNEA PUPIL CATARACT IRIS LENS RETINA MACULA OPTIC NERVE The eye on the right is at risk for all three types of AMBLYOPIA. Rays of light enter the normal eye on the left, are bent by the cornea and the lens and are focused one the most precise part of the retina called the macula. Light entering the right eye is disrupted by a congenital cataract (deprivational amblyopia). Since the right eye is shorter than the left, light doesn't focus on the retina due to unequal far-sightedness(refractive amblyopia). Since the left eye is crossed (esotropia-type strabismus), incoming light fails to align on the macula (strabismic amblyopia). ye doctors and orthoptists want each child to grow frequently suppresses or "turns off" the brain image from up with the healthiest visual system possible. the non-dominant eye. Strabismic amblyopia can be E This goal requires the close cooperation of treated by combinations of drops, glasses, patching parents, pediatricians, primary doctors, optometrists, and/or eye muscle surgery. school nurses and health aids and the professionals who DETECTION: Within the first days after birth, deal with visually impaired babies. part of each baby's first physical exam is the "red reflex" an abnormality of which could indicate cataract or tumor. At birth, a normal infant has relatively poor vision in the range A part of routine pre-school pediatric check-ups is of 20/2000! Under normal conditions, the visual system improves so that observations of red reflex by photoscreen and Brückner 20/20 vision might be attained by school age and retained after age 10 years.
    [Show full text]
  • Refractive Errors
    Refractive Errors - Epidemiology & Risk Factors (("refractive errors/epidemiology"[MAJR:noexp]) OR ("refractive errors/ethnology"[MAJR:noexp]) OR (hyperopia/epidemiology[MAJR:noexp]) OR (hyperopia/ethnology[MAJR:noexp]) OR (myopia/epidemiology[MAJR:noexp]) OR (myopia/ethnology[MAJR:noexp]) OR (astigmatism/epidemiology[MAJR:noexp]) OR (astigmatism/ethnology[MAJR:noexp]) OR (presbyopia/epidemiology[MAJR:noexp]) OR (presbyopia/ethnology[MAJR:noexp])) ((Refractive Errors[MAJR:noexp]) OR (Hyperopia[MAJR:noexp]) OR (Myopia[MAJR:noexp]) OR (Astigmatism[MAJR:noexp]) OR (Presbyopia[MAJR:noexp])) AND (Prevalence[MeSH Terms) ((Refractive Errors[MAJR:noexp]) OR (Hyperopia[MAJR:noexp]) OR (Myopia[MAJR:noexp]) OR (Astigmatism[MAJR:noexp]) OR (Presbyopia[MAJR:noexp])) AND (Risk Factors[MeSH Terms]) (("myopia/epidemiology"[MeSH Terms]) OR (("myopia"[MeSH Terms]) AND ("risk factors"[MeSH Terms]))) AND ((reading[tiab]) OR (near work[tiab]) OR (nearwork[tiab]) OR (cylinder power[tiab]) OR (optical power[tiab]) OR (accommodation[tiab])) (refractive error*[tiab] OR hyperopia[tiab] OR myopia[tiab] OR astigmatism[tiab] OR presbyopia[tiab]) AND (epidemiolog*[tiab] OR ethnolog*[tiab] OR prevalen*[tiab] OR risk factor*[tiab]) (myopia[tiab]) AND (reading[tiab] OR nearwork[tiab] OR near work[tiab]) Diagnosis – Reproducibility of Results ("refractive errors/diagnosis"[MAJR]) AND ("reproducibility of results"[MeSH Terms]) (refractive error*[tiab] OR hyperopia[tiab] OR myopia[tiab] OR astigmatism[tiab] OR presbyopia[tiab]) AND (diagnos*[tiab] OR reproducib*[tiab])
    [Show full text]
  • Association of British Dispensing Opticians Heads You Win, Tails
    Agenda Heads You Win, Tails You Lose • The correction of ametropia • Magnification, retinal image size, visual Association of British The Optical Advantages and acuity Disadvantages of Spectacle Dispensing Opticians • Field of view Lenses and Contact lenses • Accommodation and convergence 2014 Conference Andrew Keirl • Binocular vision and anisometropia Kenilworth Optometrist and Dispensing Optician • Presbyopia. 1 2 3 Spectacle lenses Contact lenses Introduction • Refractive errors that can be corrected • Refractive errors that can be corrected using • Patients often change from a spectacle to a using spectacle lenses: contact lenses: contact lens correction and vice versa – myopia – myopia • Both modes of correction are usually effective – hypermetropia in producing in-focus retinal images – hypermetropia • apparent size of the eyes and surround in both cases • There are of course some differences – astigmatism – astigmatism between modes, most of which are • not so good with irregular corneas • better for irregular corneas associated with the position of the correction. – presbyopia – presbyopia • Some binocular vision problems are • Binocular vision problems are difficult to manage using contact lenses. easily managed using spectacle lenses. 4 5 6 The correction of ametropia using Effectivity contact lenses • A distance correction will form an image • Hydrogel contact lenses at the far point of the eye – when a hydrogel contact lens is fitted to an eye, The Correction of Ametropia the lens “drapes” to fit the cornea • Due to the vertex distance this far point – this implies that the tear lens formed between the will lie at slightly different distances from contact lens and the cornea should have zero the two types of correcting lens power and the ametropia is corrected by the BVP of the contact lens – the powers of the spectacle lens and the – not always the case but usually assumed in contact lens required to correct a particular practice eye will therefore be different.
    [Show full text]